There will be a moment this afternoon, probably a few seconds before the anthems, when Mike Brown glances nervously at the human mountain range of hulking great Springboks clustered together on the far side of halfway, feels a slight loosening sensation in the pit of his stomach and concludes that all things considered, he has felt better. But England's new full-back has been here before, both figuratively and metaphorically, and as he felt a whole lot worse on the previous occasion, he is perfectly equipped to rise above the trepidation.
Five years ago, the Southampton-born Harlequin was a member of what might have been called the "red-rose irregulars": a callow, under-strength band of tourists cobbled together by the England coach Brian Ashton to confront a mighty South African side on the unforgiving terrain of the high veld in a two-Test series no one wanted to play. There were no players from the three best sides in the Premiership – Leicester, Wasps and Bath were all involved in late-season European finals – so Brown found himself winning a first cap in very strange company: a peculiar mix of ambitious young wannabes, gnarled has-beens and anonymous never-wozzers, with the odd Test-class act here and there.
By way of adding insult to injury that day in Pretoria, many of the team were suffering from an unusually vicious virus of the gastric variety. Brown was among them. "It was pretty horrible," he recalls. "I copped it the night before the first Test, felt terrible on the morning of the game and couldn't eat anything before kick-off. I don't remember much about the match itself, except thinking that no matter how ill I was, there was a job to be done and it was up to me to get on with it. Things are different now, I'm happy to say – probably because we're all paranoid. We have our own chef with us, there are bottles of sanitised gel all over the place... nothing is left to chance."
Talking of which, today's proceedings are in "main chance" territory for a player who has not started an international match since the summer of 2008. The decision of the coach Stuart Lancaster to shift Ben Foden, the senior full-back for the last couple of years, to the left wing for this highly significant confrontation with the Boks, has opened things up at just the right time, and Brown is handily placed to take full advantage. He is in the best shape of his life and the best form of his career; he is brimming with confidence after helping Quins to a first Premiership title; and he believes, not unreasonably, that the No 15 shirt is now his to lose.
"I remember feeling disappointed in '07, when I missed out on selection for that year's World Cup," he says. "But looking back, it was probably a little too early for me. I was only a season out of second-division rugby (Quins had been relegated from the top flight in 2005) and to play my first Tests in such a depleted England side... maybe the circumstances weren't the best. I was more upset at not making the squad for last year's World Cup because I felt I'd been pushing Ben pretty hard. Still, Stuart has given me this opportunity now and I'm massively grateful. I've spent so much time with him in recent seasons, there's real trust on both sides. It's important to me to repay his trust in this game."
Brown is not the lightest of the England backs on this tour but at 14st, he is not obviously the man to mix it with the big beasts of Springbokdom. Yet as anyone who watches Premiership rugby on a regular basis will testify, he has never been on the shy side when it comes to throwing his weight around. Pounds and ounces may be at a premium, but he is more than generous in dispensing it.
"People say I've calmed down a little, that I've started to pick and choose my fights," he says, laughing at the reminder that Jon Callard, one of the coaches on this tour, was known as "Mr Stroppy" during his days as a full-back with Bath and England.
"I guess that's right, although I still like to be in the middle of things. In the end, I'm just the little guy who sticks up for himself. I'm competitive – always have been – and I'd like to think that it's one of the things Stuart likes about my rugby. There are quite a few players from Harlequins in this squad and if I'm honest, we've all toughened up. It's been one of the factors in our success, unquestionably."
Interestingly, he traces this stiffening of the sinews back to Dean Richards' arrival at the Stoop in '05, which pretty much coincided with Brown's promotion to the first team as a 20-year-old after two years in the London club's spectacularly productive academy. The Great Shambling Bear's association with Quins would end in the chaos and calamity of the fake blood affair, but during his tenure he prepared the ground for future triumph.
"Dean enjoyed the feisty side of rugby, I think it's fair to say," Brown acknowledges. "My approach fitted in nicely, although I found him an intimidating figure and spent most of my time trying to keep out of his way. Since then, I've spent a lot of time with Conor O'Shea (Richards' successor as director of rugby): he's been my mentor and I can't thank him enough. I've also worked on my speed with Margot Wells (who coached her husband Alan to Olympic 100 metres gold at the Moscow Games in 1980). She's been brilliant with me. There are a few reasons why my game has improved, but Margot's input is definitely one of them."
Mostly, though, Brown has dragged himself up the hill. The last time he toured with England in the southern hemisphere, he went on an all-nighter after a heavy defeat by the All Blacks in Auckland, was late for a physiotherapy appointment as a consequence and landed himself in a small sea of hot water with Twickenham's disciplinary class. The way back has been long and hard. Understandably, he is in no hurry to look over his shoulder at the road he has just travelled.
"This," he says, "is a privilege. I felt the same way when I made my debut back in 2007, but everything is different now. I've waited for this opportunity and now it's here, I feel I deserve it. All I have to do now is justify the faith people have put in me."
It will be no easy matter, not against these opponents. But if Brown comes up short this afternoon, it will not be for the want of effort. Or of raw courage.